RADIOACTIVE pollution of a Scottish military firing range by depleted uranium (DU) has risen to the highest level for more than 10 years, according to a survey for the Ministry of Defence (MoD).

Soil on parts of the Kirkcudbright Training Area on the Solway coast is so contaminated that it breaches agreed safety limits. And the contamination is spreading, as DU fragments from shells misfired in the past start to corrode.

The contamination, revealed in a declassified scientific report passed to the Sunday Herald, was described as "very worrying" by Scottish environment minister Michael Russell yesterday.

"The Scottish government was not adequately consulted on the test firing of DU shells at Kirkcudbright," he said. "I have stated in the past that I am strongly opposed to the testing of such weapons on Scottish soil and this remains the case."

More than 6000 DU shells were fired at the range near Dundrennan in Dumfries and Galloway between 1982 and 2004. Controversy flared again last month when the MoD test-fired another 20 DU rounds over two days.

Scientists from the Defence Science and Technology Laboratory at Porton Down in Wiltshire have been monitoring the Kirkcudbright range every year. A copy of their latest 46-page report, covering 2006, was recently placed in the House of Commons library in London.

According to the report, there was DU contamination in soil samples from three sites on the range. The highest registered 1384 millibecquerels of radioactivity per gram, which is worse than the contamination in any of the soil samples taken since comparable monitoring began in 1996.

Two samples breached the "investigation level" agreed by the government's Depleted Uranium Firing Environmental Review Committee. Two other samples were above, or close to, the much higher "action level" agreed by the committee.

Contamination at India Target on the range was "an order of magnitude higher than results obtained in previous years", said the MoD report.

One explanation was that some DU fragments on the surface had corroded and sunk into the soil.

The report also revealed that attempts to find DU shells which had misfired in the past had failed "despite extensive searching". Control measures prevented public access to the contaminated areas, it said, and radiation doses were assessed to be "negligible".

But the MoD was accused of a "shocking disregard" for the environment by a London-based environmental policy consultant, Dr David Lowry. "The MoD should make a promise never to fire these deadly shells again," he declared.

"Of course they say that no harm has been done, but we won't know the full long-term effects of this contamination for years. We do know already that the DU shells fired in the invasion of Iraq have caused serious health implications."

An MoD spokeswoman, however, insisted that surveys had shown "only a few localised areas of DU contamination" at Kirkcudbright. "While the DU levels are well below anything that could be considered a health or environmental hazard, access to these areas is restricted," she said.

The Sunday Herald reported last month that earthworms from the range had been found to contain significant levels of DU.